<template>
  <div class="spec-preview">
    <img :src="imgs.imgUrl" />
    <div class="event" @mousemove="showShop"></div>
    <!-- 放大镜 -->
    <div class="big">
      <img :src="imgs.imgUrl" ref="bigImg"/>
    </div>
    <!-- 遮罩层 ref的作用就是取代了原生js直接操作dom-->
    <div class="mask" ref="mask"></div>
  </div>
</template>

<script>
  export default {
    name: "Zoom",
    props:['skuImageList'],
    data() {
      return {
        index:0
      }
    },
    computed:{
      imgs(){
        return this.skuImageList[this.index]||{};//解决服务器数据返回带来的undefined问题
      }
    },
    methods: {
      showShop(e){
        //获取的还是原生dom元素
        // console.log(this.$refs.mask)
        var left=e.offsetX-this.$refs.mask.offsetWidth/2;
        var top=e.offsetY-this.$refs.mask.offsetHeight/2;
        if(left<0)left=0;
        if(left>this.$refs.mask.offsetWidth)left=this.$refs.mask.offsetWidth;
        if(top<0)top=0;
        if(top>this.$refs.mask.offsetHeight)top=this.$refs.mask.offsetHeight;
        this.$refs.mask.style.left=left+"px";
        this.$refs.mask.style.top=top+"px";
        this.$refs.bigImg.style.left=-2*left+"px";
        this.$refs.bigImg.style.top=-2*top+"px";
      },
    },
    mounted() {
      //兄弟间通信可以使用全局事件总线
      this.$bus.$on('changeImage',(data)=>{
        this.index=data;
      });
    },
  }
</script>

<style lang="less">
  .spec-preview {
    position: relative;
    width: 400px;
    height: 400px;
    border: 1px solid #ccc;

    img {
      width: 100%;
      height: 100%;
    }

    .event {
      width: 100%;
      height: 100%;
      position: absolute;
      top: 0;
      left: 0;
      z-index: 998;
    }

    .mask {
      width: 50%;
      height: 50%;
      background-color: rgba(0, 255, 0, 0.3);
      position: absolute;
      left: 0;
      top: 0;
      display: none;
    }

    .big {
      width: 100%;
      height: 100%;
      position: absolute;
      top: -1px;
      left: 100%;
      border: 1px solid #aaa;
      overflow: hidden;
      z-index: 998;
      display: none;
      background: white;

      img {
        width: 200%;
        max-width: 200%;
        height: 200%;
        position: absolute;
        left: 0;
        top: 0;
      }
    }

    .event:hover~.mask,
    .event:hover~.big {
      display: block;
    }
  }
</style>